Antenna Cable Loss and SWR

Introduction.
To measure the cable loss, you should disconnect the other end of the cable from the antenna - for an open line system condition. Yet it is necessary to know what is the exact cable length in meters.

1st (ground) case. Cable Loss from SWR

For instance SWR=3 at cable length of 30 meters, we get 10 dB/100m.
In normal case, the typical values for 145 MHz is as follows:
- for RG-58C/U = 23.5 dB/100m ; for RG-213/U = 8.0 dB/100m

2nd case. SWR from the Cable Loss
If you want to know what the checked SWR should be for a length of cable in meters of which you know the loss in decibels per 100 meters (the OEM's data) :